Manufactured tobacco and smoking articles are well-known. See, e.g., U.S. Pat. Nos. 235,885; 235,886; 2,433,877; 2,445,338; 2,485,670; 2,592,553; 2,598,680; 3,085,580; 3,098,492; 3,203,432; 3,209,763; 3,223,090; 3,298,062; 3,313,003; 3,353,541; 3,364,935; 3,373,751; 3,404,690; 3,404,691; 3,410,279; 3,528,434; 3,529,602; 3,894,544; 3,931,824; 3,932,081; 4,083,371; 4,233,993; 4,333,484; 4,340,072; 4,347,855; 4,391,285; U.S. Defensive Publication No. T912,011; German Publication Nos. 1,167,717; 1,532,104; 1,782,854; 2,358,657; 2,410,168; and 2,633,627; Canadian Pat. No. 951,209; U.K. Publication Nos. 282,369 and 2,064,296; Swiss Pat. No. 275,420; Belgian Publication No. 828503; South African Publication No. 69/838; Netherlands Publication No. 143,799; and commonly assigned U.S. Pat. No. 4,510,950, issued Apr. 16, 1985, each of which is hereby incorporated by reference in its entirety. Some of those documents refer to extrusion of strands or filaments of tobacco or to extrusion of tobacco rods containing axially directed air channels.
One approach to making a foamed, extruded smoking article is disclosed in commonly assigned U.S. Pat. No. 4,510,950 and co-pending and commonly assigned U.S. patent application Ser. No. 723,883 filed April 16, 1985. The smoking article is typically substantially cylindrical and is extruded under conditions such that the water in the wet blend fed to the extruder die is converted to steam, thereby foaming the article. The article is monolithic, that is, it is extruded as a single strand with a diameter of typically about 8 mm if the article is a cigarette.
Although that article represents an advance over the art, in certain cases the article has been found to soften sufficiently during smoking to cause the article to collapse. Additionally, in some cases the resistance-to-draw (RTD) of the article has been too high and/or difficult to control.
Accordingly, there is a continuing need for smoking articles that can be manufactured easily, whose RTD and other physical properties can be easily controlled within desired ranges, and which are well accepted in the marketplace.